1. Field of the Invention
The present invention generally relates to an optical recording method and apparatus and, more particularly, to an optical recording method and apparatus using a rewritable optical recording medium which has previously recorded address information.
2. Description of the Related Art
Recently, a digital versatile disc-rewritable (DVD-RW) has attracted considerable attention as one of rewritable optical recording media.
A blank or brand new DVD-RW has previously recorded address guide information which is referred to as LPP address. The LPP address is provided by forming land pre-pits on a recording surface of the DVD-RW. A recording operation is performed by forming recording pits on the recording surface of the DVD-RW by referring to the LPP address. A group of recording pits form a sector which represents 2-kilobyte user data. An address (sector address) is assigned to each sector. Normally, the LPP address matches the sector address.
A minimum unit of data recorded on the DVD-RW is referred to as a block which normally includes 16 sectors. It is possible to record information (recording pits) over a plurality of blocks by a single continuous recording operation. However, when a recording operation for adding information to previously recorded information or an overwriting (rewriting) operation is performed on the DVD-RW, a link is generated between a previously recorded block and a newly recorded block. According to the nature of the link, user data cannot be recorded in the link part. There are various sizes (lengths) for the link such as a 0-kilobyte link, a 2-kilobyte link or a 32-kilobyte link.
According to the 0-kilobyte link, there is no unusable area in the link part. However, a drive margin in the link part is small, and a high accuracy is required for setting a start position of a recording operation. Additionally, a service life of the disc may be shortened since a start position of recording cannot be shifted and recording is performed many times in the same link part.
According to the 32-kilobyte link, a recordable area corresponding to 32 kilobytes (16 sectors) is assigned to the link part. When the 32-kilobyte link is used, reliability of the user data is high. However, since a large recordable area is assigned to the link part, an amount of information recordable on a single DVD-RW is extremely reduced.
According to the 2-kilobyte link, a recordable area corresponding to 2 kilobytes (one sector) is assigned to the link part. The 2-kilobyte link has an advantage in that a sufficient margin is provided by the link part while an amount of information recordable on a single DVD-RW is not greatly reduced as is in the case of the 32-kilobyte link.
As a method for achieving the 2-kilobyte link, there are an internal link method and an external link method. According to the internal link method, the link part is included in a block. Accordingly, if the block contains 32 kilobytes, user data included in a single block is 30 kilobytes. (16xc3x972 kilobytesxe2x88x922 kilobytes=30 kilobytes) On the other hand, according to the external link method, the link part is provided outside the block. Thus, the user data in a single block remains unchanged, that is, the user data included in a single block is 32 kilobytes.
Generally a computer treats data by a power of two. A filing system using a conventional optical information recording medium is also based on such a data structure. In the internal link method, user data becomes a multiple of 30 kilobytes which is not a power of two. Thus, there is a problem that the internal link method is inconvenient for a conventional filing system. On the other hand, since the user data treated by the external link method is 32 kilobytes, the external link method is easily applicable to a conventional filing system.
When data is recorded by the external link method using 2-kilobyte link (hereinafter, referred to as 2-kilobyte external link method), the link part corresponding to a single sector (2 kilobytes) is provided between adjacent blocks. Accordingly, a sector address which is recorded with the use data shifts from the previously recorded LPP address. As mentioned above, a unit of data recorded on the DVD-RW corresponds to a block which contains 16 sectors. Thus, an address of a first sector of a block must be a multiple of 16. More specifically, an address of a first sector of a block must be XXX0h, and an address of the last sector in the same block must be xxxFh (xxx is an arbitrary hexadecimal number). In the 2-kilobyte external link method, the link part is provided outside the block. Thus, in order to give an address which is a multiple of 16 to a first sector of a block, an address cannot be assigned to the link part. That is, a link part which is not given an address exists between adjacent blocks. As a result, when data is recorded by the 2-kilobyte external link method, the sector address recorded with the user data shifts from the previously recorded LPP address. If such a shift occurs between the sector address and the PLL address at an arbitrary position on the DVD-RW medium, it is very difficult to calculate an address. Accordingly, there is a problem in that a recording or overwriting cannot be freely performed. Thus, although the 2-kilobyte link method is superior to other methods with respect to application to a conventional filing system, the 2-kilobyte external link method cannot be used in practice.
In a conventional recording method such as a disc-at-once method or an incremental write method, there is no link or the 0-kilobyte link, 32-kilobyte link or an internal link method using 2-kilobyte link is used. As a result, the sector address matches the LPP address. That is, a relationship between the sector address and the LPP address differs from the conventional recording method to the 2-kilobyte external link method. Thus, if an initial recording is performed by one of the methods, the same method must be used thereafter until whole recorded data is erased.
As a method for erasing recorded information on the DVD-RW, a physical erasing method or a logical erasing method may be used. In the physical erasing method, the recording pits are physically erased. In the logical erasing method, a specific pattern such as all-0 is recorded so as to substantially (logically) erase previously recorded pits. According to the nature of the DVD-RW, a service life of the DVD-RW can be longer when the logical erasing method is used than when the physical erasing method is used. As mentioned above, in the logical erasing method, an erasing pattern (erasing data) is recorded so as to erase recorded data, the sector address is recorded together with the erasing data. In order to facilitate address calculation, the sector address is recorded to match the LPP address so that the use of the DVD-RW after erasing becomes easy.
Generally, in an optical recording apparatus, when recording or overwriting is performed, a present address is recognized by reproducing both the sector address and the LPP address. Accordingly, there is a problem when data is recorded or overwritten on an erasing pattern by the 2-kilobyte external link method. This is because the erasing pattern is recorded according to the sector structure and the sector address matches the LPP address while the sector address of the sector recorded by the 2-kilobyte external link method shifts from the LPP address. Accordingly, when data is recorded or overwritten, the address of the previously recorded sector must be distinguishable from the LPP address so as to seek a target address from which the recording or overwriting operation is started.
It is a general object of the present invention to provide an improved and useful optical recording method and apparatus in which the above-mentioned problems are eliminated.
A more specific object of the present invention is to provide an optical recording method and apparatus which can record information on a rewritable recording medium having a pre-recorded address guide by the external link method without performing complex calculations.
Another object of the present invention is to provide a rewritable optical recording medium which can be recorded by the external link method without complex calculations.
In order to achieve the above-mentioned objects, there is provided according to one aspect of the present invention a method for recording information on a rewritable optical recording medium having a pre-recorded address guide, the method comprising the steps of:
recording data on the rewritable optical recording medium on an individual block basis along the pre-recorded address guide, the block including a predetermined number of sectors each of which has a consecutively numbered sector address; and
recording a link part having a predetermined fixed length between adjacent blocks, the link part lacking an address so that the sector address shifts from an address indicated by the pre-recorded address guide by the length of said link part.
According to this invention, by providing the link part having a length corresponding to a single sector such as 2 kilobytes, a large margin between the adjacent blocks can be maintained at the link part while an efficiency of use of the recordable area of the recording medium is maintained at a relatively high level. Thus, recording can be freely performed on an individual block basis. Additionally, since the minimum recording unit which corresponds to a single block is fixed, a relationship between the address indicated by the pre-recorded address guide and the sector address becomes simple. That is, the sector address shifts from the address indicated by the pre-recorded address guide according to a simple rule, and, thereby, the calculation of address can be simple. Accordingly, the external link method in which the link part is provided outside the recording unit can be used in practice.
Additionally, the method according to the present invention may further comprise the step of:
erasing data recorded on the rewritable optical recording medium before rewriting new data, the erasure being performed by recording erasing data having a predetermined erasing pattern, the erasing data including the sector address so that the sector address in the erasing pattern matches the address indicated by said pre-recorded address guide.
Accordingly, the calculation of an address after the erasure of previously recorded data becomes simple since the address in the erasing data matches the address indicated by the pre-recorded address guide.
Additionally, the method according to the present invention may further comprise the steps of:
determining whether or not data recorded at a currently reading position on the rewritable optical recording medium is the erasing data;
recognizing the currently reading position from the sector address in the erasing data when the data recorded at the currently reading position is the erasing data; and
recognizing the currently reading position by a predetermined calculation based on the sector address when the data recorded at the currently reading position is not the erasing data.
Accordingly, the currently reading position on the recording medium can be accurately recognized by a simple calculation regardless of whether or not the data recorded at the currently reading position is the erasing data. Thus, a target address can be accurately reached based on the currently reading position.
Additionally, there is provided according to another aspect of the present invention an optical recording apparatus using a rewritable optical recording medium having a pre-recorded address guide, the optical recording apparatus comprising:
a light beam source projecting a light beam onto the rewritable optical recording medium so as to record data on or reproduce data from said rewritable optical recording medium;
a reproducing unit reading data recorded on the rewritable optical recording medium, the data being read based on the light beam reflected by the rewritable optical recording medium;
a recording unit recording data on the rewritable optical recording medium on an individual block basis along the pre-recorded address guide, the block including a predetermined number of sectors each of which has a consecutively numbered sector address, the recording unit recording a link part having a predetermined fixed length between adjacent blocks, the link part lacking an address so that the sector address shifts from an address indicated by the pre-recorded address guide by the length of the link part;
determining means for determining whether or not data recorded at a currently reading position on the rewritable optical recording medium is erasing data having a predetermined erasing pattern;
first recognizing means for recognizing the currently reading position from the sector address included in the erasing data when the data recorded at the currently reading position is the erasing data; and
second recognizing means for recognizing the currently reading position by a predetermined calculation based on the sector address when the data recorded at the currently reading position is not the erasing data; and
seeking means for seeking a target address by recognizing the currently reading position by one of the first recognizing means and the second recognizing means.
Accordingly, the currently reading position on the recording medium can be accurately recognized by a simple calculation regardless of whether or not the data recorded at the currently reading position is the erasing data. Thus, a target address can be accurately reached based on the currently reading position.
Additionally, there is provided according to another aspect of the present invention a rewritable optical recording medium having a pre-recorded address guide, comprising:
data recorded on an individual block basis along the pre-recorded address guide, the block including a predetermined number of sectors each of which has a consecutively numbered sector address; and
a link part having a predetermined fixed length and provided between adjacent blocks, the link part lacking an address so that the sector address shifts from an address indicated by the pre-recorded address guide by the length of said link part.
Other objects, features and advantages of the present of the resent invention will become more apparent form the following detailed description when read in conjunction with the accompanying drawings.